Field of the Invention
The present invention relates to the field of the broadcast transmissions for the distribution of audio and/or video contents, and particularly it relates to Electronic Program Guides (EPG) for such broadcast transmissions.
Description of the Related Art
From now on, with the generic term of “broadcast transmission” it will be intended the distribution of identical audio and/or video contents to a same group of viewers. Actually, the term “broadcast transmission” implies that the recipients of the audio and/or video contents coincides with the totality of viewers capable of receiving such contents; if the recipients of such transmission are a subgroup thereof, a more correct term would be “multicast transmission”; however, for the sake of conciseness, the term “broadcast transmission” will be indistinctly employed for describing both the two abovementioned cases.
This distribution of audio and/or video contents may be carried out by means of radio frequency signals (such as in the terrestrial television, in the satellite television or in the cable television), and/or by exploiting a packet-switched network infrastructure like the Internet (such as in the Internet Protocol Television (IPTV)).
A segment of audio and/or video contents transmitted by a broadcasting center—or, simply, “broadcaster”—define a corresponding program, such as a television show, a film, an episode of a television series or a news show. Typically, the programs are organized by the broadcaster in a daily, weekly, or season-long schedule, also referred to as time scheduling.
A broadcast transmission of a program may provide for the simultaneous distribution of the audio and/or video contents together with auxiliary metadata giving information about the contents itself. Particularly, in the modern broadcast transmissions complying with the Digital Video Broadcasting (DVB) standards suite, information about the time scheduling is transmitted simultaneously with the audio and/or video contents in the form of a so-called Electronic Program Guide (EPG).
An EPG is an on-screen guide exploitable by the user (generally referred to as the “television viewer”) for navigating the time scheduling in order to obtain information regarding the programs to be transmitted, such as their scheduled start/end times, the durations thereof, the channel on which they will be transmitted and so on. Through an EPG, a television viewer may advantageously set a Personal Video Recorder (PVR)—i.e., a device that is able to record audio and video contents to a disk drive, an USB flash drive, a memory card or other memory mediums—so as to plan in advance the recording of programs to be transmitted in a later time. Moreover, the services offered by an EPG may be advantageously exploited by other apparatuses, such as set-top box systems, Digital Media Receivers (DMR) and media centers.
Whether the EPG is transmitted within the broadcast stream—i.e., conveyed on the same communication channel through which the audio and video contents are distributed —or it is conveyed on a dedicated communication channel, the updating thereof is typically performed from time to time, and not necessarily every time a new program is started. Thus, the audio and/or video contents that are actually transmitted may correspond to a program that is different from the one indicated in the time scheduling provided by the EPG; typically, the program actually transmitted may correspond to the program that precedes or follows the program provided by the EPG. This difference may be caused by several factors, such as a commercials' duration modification or a sudden removal of a complete scheduled program.
Therefore, the information provided by the EPG generally does not fully correspond to the actual audio and/or video contents that are transmitted. In other words, the EPG is generally desynchronized with the actual broadcast transmission. The arise of a temporal gap between the time scheduling provided by the EPG and the actual broadcast transmission negatively affects any possible two-way interactivity between television viewers and broadcasters. Indeed, from the television users' side, the efficiency of EPGs in the setting of PVRs become more scarce; on the other side, the broadcasters are no more able to efficiently monitor the television users' activity (i.e., the identification of which programs were actually viewed by the television viewer) based on the EPG information.
In order to increase the reliability of EPGs, two different main approaches have been employed in the art.
Specifically, according to a first known approach, a new EPG is generated and transmitted to the television viewers every time a time scheduling modification is issued by the broadcaster. An example of an approach of this type is provided by Florical System, which, through its products named AirGuide and AirBoss, allow the broadcasters to distribute updated EPGs. Specifically, AirBoss is a play-to-air automation system that allows the broadcasters to perform a real time scheduling of content distribution; the AirGuide system is instead configured to read scheduling information to be exploited by the AirBoss system. All this real time data gathered by such systems is exploited to generate the EPG in a customizable fashion, which is then multiplexed in the broadcast stream. This system is currently used by some international broadcasters, such as ABC television.
According to a second known approach disclosed in the U.S. Pat. No. 6,571,053, each program is associated with a unique corresponding identification code; when a certain program starts, the broadcaster transmits the identification code associated with the program, in such a way to be automatically recognized by the PVR of the television viewer by performing an identification code matching. Unlike the previously described approach, which provides for continuously distributing data in order to update the EPG in real time, this solution provides for signaling the actual start of a given program. More specifically, each program is associated with a unique identification code; the time scheduling, together with the various identification codes, is distributed in advance by means of an EPG, or through other means, such as a TV guide provided by a newspaper or a magazine. When a television viewer yearns for recording a specific program through its PVR, he/she has to program the latter using the corresponding identification code taken from the EPG or the TV guide. Just before the actual start of a new program, the broadcaster sends the corresponding identification code to the PVR. As soon as the identification code sent by the broadcaster matches the identification code programmed into the PVR, the latter starts the recording; then, the recording is stopped when the PVR receives from the broadcaster the identification code of another, different program. Compared to the previously described system, this one requires less resources, but it is far less versatile and requires a deep user interaction.
The international patent application WO 2004/04360 discloses a synchronization system and method. The synchronization system comprises a specification unit for specifying synchronization signals associated with an audiovisual program, the latter comprising an audiovisual content and control information, a recognition unit for recognizing the synchronization signals in a transmitted stream carrying this program, by recognition of at least one extracted portion of the audiovisual content, and an activation unit triggering an action in case of detection of these signals. The specification unit prepares and transmits to the recognition unit recognition elements making it possible to obtain this extracted portion, as well as at least one action timeout lag in case of detection of the synchronization signals. The recognition or activation unit then delays the triggering of this action according to the lag transmitted, in case of detection of the synchronization signals. In variants, the timeout lag is determined and/or the recognition elements are obtained independently of the specification unit.